audioguru

Hi Antey,
We are friends so ask what you want. :lol:

It is difficult making a very high frequency radio transmitter without having a printed circuit board and detailed instructions. Perhaps it is best for you to learn by making a kit that comes with all special parts, a printed circuit board and detailed instructions. :lol:

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Uncle $crooge

zachtheterrible

Layout at 100MHZ isnt extremely critical, like in the GHZ region. Just make sure that you keep your leads real nice and short and you should be fine. And try to place the components as close together as possible on the veroboard.

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I'm no electronics god, i just talk too much.

Antey

That's what I expected, but it's always nice to get a confirmation

Well, thanks again

Heh... well... the problem is, that in this particular it's not about learning but earning a passing grade, and worse, one must distinguish between those two. Quite silly, isn't it ? For my twice-bad-luck I've come across a "teacher" who doesnt' seem to know much more than anyone in the class.
(other teachers, at lab, or lecture, are very knowledgeable, but too busy to help ). My task is to provide 3 different schematics of FM modulator (100 MHz carrier and 50 kHz deviation ), which both look realistic, and work perfectly in simulator, then preapare detailed calculations and working (under Spice A/D 6.3 ) simulation of one of them.

I read some books, looked at few sites and groups, and run about 50 different circuits in simulator. Still nothing and the clock is ticking. So I decided that, because of obvious falult in simulator (which doesn't work at all under WinXP, so i had to switch to SIMetrix ) I'll try to read more about those sim-glitches(inconsistencies?) in book about SPICE itself then deliver results, assebled & working circuit (with credits included - honesty 1st! ), and explanation of difference between sim and reality, including the conclusion that the task itself was faulty and then wait for reaction. I don't expect to pass, but at least to get some arguments for the Dean to get permission to take this course once more, under sombody else's guidance.

I think that I took up real electronics far too late :cry: . So as one Russsian Prime Minister once said " I did my best... yet performed as usually".

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Best Regards, Peter

Soy un hombre muy honrado... :|

Nigel Goodwin

The usual way of providing FM modulation is to use a varactor diode as part of the oscillators tuned circuit, applying the audio to the varactor changes it's capacitance and provides frequency modulation.

Doing it that way will allow you to do detailed calculations, and should simulate without any problems.

The crude FM 'bugs' are far more difficult to calculate, not to mention describe - the modulation method is crude, and probably gives both FM and AM at the same time.

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PIC programmer software, and PIC Tutorials at:
http://www.winpicprog.co.uk

Antey

Anyway, I'll have three long months to make it work - I tried to run several circuits with diodes... and nothing. One of many problems is that generation dies after disconnecting the modulating tone. I know that generators sometimes require additional "kick" to start working, but it's not also the case...

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Best Regards, Peter

Soy un hombre muy honrado... :|